On our 35 footer we carry a slat floor roll up inflatable, a 7.5 foot Zodiac. Since we also carry a pair of 9.5 foot plastic kayaks, the dinghy spends most of its time rolled up in the forepeak.
We break it our when we have company, or have to make a major shopping expedition. It takes maybe 5-10 minutes to pump up, or to restow. Since we do have the kayaks for normal shore duty we only have to do this a few times a year.... so for us it's no biggie.
We also carry a 3.5 hp o'b for those days we need the dinghy.. no way you're going to plane with the soft floor anyway, so no need for power. We can carry 4 adults but only in calm conditions.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)